Duke Lacrosse DNA: Mystery Man Revealed

The second round of DNA test results in the Duke University rape investigation show "no conclusive match'' to any lacrosse players, defense attorneys said, but a vaginal swab of the alleged rape victim produced DNA from a "single male source'' -- a man not on the lacrosse team who did not attend a March 13 party that was the site of the alleged rape.

Defense attorney Joe Cheshire declined to identify the mystery man or his connection to the alleged victim, but ABC News' Law and Justice Unit has learned that the unnamed source of the DNA is the alleged victim's "boyfriend," according to her mother.

ABC News is withholding the name of the man because he is apparently not a target of the investigation. Records indicate that Durham, N.C., police gave the "boyfriend'' a cheek swab to collect DNA on May 3, ABC News' Law and Justice Unit has learned exclusively.

It is unclear if or how the first DNA tests missed what appears to be the only foreign genetic material found on the alleged victim's body, defense attorneys said. Two Duke lacrosse players were indicted more than two weeks before the cheek swab was taken from the "boyfriend."

It is also unclear whether the alleged victim had sex with the "boyfriend" the night she claims to have been raped by three Duke lacrosse players. DNA experts tell ABC News that genetic traces of semen can remain in the body up to six days after intercouse.

Defense attorneys declined to release the actual report, saying that it contained the name of the "single male source.''

Durham District Attorney Mike Nifong did not return a call to his home Friday night requesting his reaction to the defense attorneys' press conference. Nifong has said recently that he would be undeterred by a lack of conclusive DNA evidence.

Experts say that the absence of conclusive DNA evidence would not necessarily be a fatal blow to the prosecution's case. They cite a figure stating that 75 percent to 80 percent of rape prosecutions do not involve forensic evidence such as DNA.

"The truth is if you speak to crime lab directors, they will tell you that in only a relatively small number of cases is there any DNA evidence," said Peter Neufeld, co-founder and co-director of the Innocence Project, which uses DNA to free people wrongly imprisoned. "In rape cases, there is an expectation of DNA. But like many expectations, often it is misplaced."

According to defense attorneys, neither Colin Finnerty nor Reade Seligmann, the two men charged, appear anywhere in the latest report. The two were charged with rape, kidnapping and sexual assault. None of either men's DNA has turned up in any test results, defense attorneys said.

Chesire conceded Friday that the results show that genetic material from beneath a plastic fingernail recovered from a garbage can at the scene of the alleged crime has "some characteristics'' of "one or two'' players' DNA, but that none of the tests show any conclusive matches. He acknowledged that the report names a third player, but declined to identify that player.

On Thursday, ABC News reported that prosecutors believe they have DNA evidence that could link a third player to the alleged attack.